Anyone know if it's possible to patch the Color Classic's ROM to remove the 10MB RAM cap?
Or is the limit done is software by the OS?
Or is the limit done is software by the OS?
Color Classic Max RAM
- Thread starter chrisdaun
- Start date
From what I understand of that cap it comes from the ROM being mapped starting at the 10MB address and thus expecting to from functions to be in that range. Moving it would be a serious reengineering of the ROM and potentially breaking some apps that naughtily call into the ROM directly. The mapping is almost certainly done by fixed logic that would have to be replaced, and is probably embedded in a custom chip. Apple probably didn't wire up an unnecessary address lines to the SIMM slots to be able to use bigger sticks either.
That’s too bad. I was hoping that is was possible to develop something the BMOW rom-inator-ii custom ROM for the Color Classic
And there were a lot of discussions in this matter such as this thread over at the 68kmla. The limit seems to be mostly due to the 24-bit address lines that limit the amount of memory supported.
68kmla.org
Attempt to break the 10MB limit on the Classic II
I was looking at the way the memory is setup in the Classic II, and it finally dawned on me why the RAM is limited to 10 MB. They only used 24 address lines! As such, 10 MB RAM + 4 MB ROM leaves 2 MB of addressable space for things like VRAM, etc... through the EAGLE Gate Array chip. That's...
68kmla.org
It's always funny to click links and find out I wrote the post years ago and completely forgot I did so.
It's a good thing 68kMLA goes back as far as it does. If I didn't write some of this stuff down I'd have forgotten it by now.
It's a good thing 68kMLA goes back as far as it does. If I didn't write some of this stuff down I'd have forgotten it by now.
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It is really nice. I went back and read some of my old posts over there and discovered I had done some upgrades to my machines that I had COMPLETELY forgotten about!